Isn't it conceiveable that spacetime is actually flat but the clocks and rulers we use to measure it are actually rubbery?...yes...Both viewpoints give precisely the same predictions for any measurements performed...Some problems are are solved most easily and quickly using the curved spacetime paradigm; others, using the flat spacetime...Black hole problems, for example, are most amenable to curved spacetime techniques; gravitational wave problems (for, example computing the waves produced when two neutron stars orbit each other) are most amenable to flat spacetime techniques...the laws that underlie the two paradigms are mathematically equivalent...That is why physicsts were not content with Einstein's curved spacetime paradigm and have developed the flat spacetime paradigm as a supplement to it...
Blenton said:How then could we explain gravitational lensing in a flat spacetime? I don't think my eyes would be rubbery. :D
It's going in a straight line in GR. I don't really know the alternative theory, but it sounds like the path is curved in that one.NWH said:This kind of fits into what I've been thinking... Is light really curved by space? Or is it still going in a straight line? I assume it's both...
Fredrik said:It seems that in this case, we have an alternative theory's equivalent to GR, at least in the sense that it makes the same predictions about the results of experiments, but probably also in the sense that the axioms of either theory can be derived from the axioms of the other.
Spacetime is a mathematical concept that combines the three dimensions of space and the dimension of time into a single entity. It is a fundamental aspect of Einstein's theory of general relativity, which explains how gravity works. According to this theory, mass and energy warp or curve the fabric of spacetime, causing objects to follow curved paths in space.
There is strong evidence for the curvature of spacetime, including observations of the bending of light by massive objects, such as stars and galaxies. The predictions of general relativity have also been confirmed through various experiments and observations, providing further evidence for the curvature of spacetime.
When we say that spacetime is curved, we mean that the geometry of spacetime is not flat and can be affected by the presence of mass and energy. This curvature is described by the mathematical equations of general relativity and can be visualized as a stretched or warped grid that determines how objects move in space.
According to general relativity, the curvature of spacetime is not constant and can vary depending on the distribution of mass and energy in a given region. In some regions, spacetime may be relatively flat, while in others it may be highly curved. The amount of curvature also depends on the strength of the gravitational field in that region.
In the context of general relativity, it is not possible for spacetime to be completely uncurved. However, in certain regions where there is no matter or energy present, the curvature of spacetime may be negligible and can be approximated as flat. This is known as the flat spacetime limit and is often used in simpler calculations and models.